JP3151037B2 - Pneumatic radial tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and more particularly to a radial tire having improved durability by improving a belt for reinforcing a tread thereof.

[0002]

2. Description of the Related Art A belt of a radial tire is generally used as a rubberized layer in which reinforcing elements made of steel cords or steel filaments, which are arranged obliquely parallel to the equatorial plane of the tire, are usually embedded at equal intervals.

[0003]

In the conventional belt in which the parallel arrangement of the reinforcing elements is arranged at regular intervals, the rubber facing the end of each reinforcing element at the width end of the belt layer is connected to the ground of the tire. Since it is poked every time it is deformed, a fine crack is generated.
That is, there is no plating layer on the end face of each reinforcing element at the width end of the belt layer, and since this end face and rubber are not bonded, the terminal of the reinforcing element pecks the rubber facing it due to the ground deformation at the time of rolling the tire. This is where the rubber peels and subsequently grows into fine cracks. The cracks eventually grow between adjacent reinforcing elements, and then spread between the stacks of belts. This crack propagation proceeds rapidly with the help of shear strain generated between the belt layers during rolling of the tire under load, and the rate of crack propagation leading to so-called belt separation increases significantly, which increases the durability of the radial tire. Determine.

Here, it is important to suppress the growth of cracks in the process of straddling the reinforcing elements described above,
For this purpose, it is naturally advantageous to increase the distance between adjacent reinforcing elements. On the other hand, in order to simplify the required cord in addition to the strong demand for reducing the weight of the tire, the wire diameter of the reinforcing element is reduced. As a result, in order to maintain the same tire strength, there is no other way than to increase the number of driving of the reinforcing elements, and the interval between the reinforcing elements is rather narrow, which is incompatible with the suppression of crack growth.

[0005] Also, from the standpoint of resource saving, the tires have been rehabilitated and used several times, and the tread compounds have been improved, so that the total life of the tires has been remarkably increased. However, improving belt durability is an urgent matter. Therefore, it is necessary to provide an effective and appropriate solution to the deterioration of belt durability caused by the subsequent growth progress of a fine crack generated in the rubber at the width end of the belt layer facing the end of the reinforcing element. SUMMARY OF THE INVENTION It is an object of the present invention to provide a radial tire with an improved belt layer which can advantageously be adapted to this problem.

[0006]

The above object is achieved by the following first object.
And 2 are properly achieved by the invention. That is, the first aspect of the present invention relates to a steel which is arranged obliquely parallel to the equatorial plane of the tire.
Cord, organic fiber cord or organic fiber monofilament
A pneumatic radial tire provided with a belt which is subjected to the tread reinforcement of the tire according to rubberized layer of reinforcing elements by instrument, at least one layer of the belt, of the said reinforcing elements individually and independently occupy that layer , Less than half
By dividing the above reinforcing elements into bundles of several or less,
The dispersion spacing between the bundle and the reinforcing element adjacent thereto, the
When the reinforcing elements are arranged at equal intervals,
Is an array of reinforcing elements Ru spread compared, at least one reinforcing element in each bundle is shifted in the tire radial direction, of a line parallel to the contour of the belt layer each bundle is embedded, the The bundle thickness defined by the distance between the outermost contact line and the innermost contact line in the tire radial direction of the bundle is defined as 1 of the reinforcing element diameter.
A pneumatic radial tire characterized in that the number is more than twice and less than twice.

Wherein the bundle is composed of the same number of reinforcement elements, the bundle is composed of different numbers of reinforcement elements, and at least some of the reinforcement elements adjacent in the bundle are arranged in contact with each other; Each case in which the spacing between adjacent reinforcing elements in the bundle is smaller than the dispersion interval of the bundle is included.

A second invention is a pneumatic radial tire having a belt layer used for reinforcing a tread of a tire as a rubberized layer of cords which are obliquely arranged in parallel to an equatorial plane of the tire. at least one layer vital structure with no wrap filament code among the code isolated individually occupying that layer, more than half of the
By dividing the code into several bundles, the distribution interval between the bundle and adjacent codes is
A pneumatic radial tire characterized by comprising a Ru <br/> sequence spread than the distance between each code in the case of equally spaced array.

[0009]

In order to prepare a rubberized layer of a reinforcing element made of cord or monofilament as a belt used in the present invention, a belt treat is first formed by a calendering roll in which a comb-shaped roll is particularly improved. This comb-toothed roll thereby serves to combine the reinforcing elements with the rubber sheet by means of a calendering roll with juxtaposed arrangements of several reinforcing elements, for example every two bundles.

The comb-shaped roll has a plurality of circumferential grooves for the above-mentioned arrangement of the reinforcing elements, the circumferential grooves being delimited by collar-shaped comb teeth for extending between adjacent ones of the section bundles. Has a groove width corresponding to a section bundle of two individually independent reinforcing elements which are in contact with each other without restriction. Further, in order to prevent the reinforcing elements from being crushed by rubber and being arranged side by side in the belt width direction when passing through the calender roll, it is preferable to apply a predetermined tension to the reinforcing elements and calender them. Further, in order to shift the reinforcing elements in the bundle in the tire radial direction, the thickness of the bundle is adjusted by appropriately adjusting the groove depth of the comb-shaped roll.

When the belt treat thus produced is used for reinforcing the belt, the treat width is cut obliquely in accordance with the required inclination of the reinforcing element with respect to the equatorial plane of the tire, and then the ears at the width ends of the treat are separated from each other. Is re-joined, wound around a raw coil together with a liner, and then subjected to a tire building process.

[0013]

As described above, the process of breaking the rubber at the width end of the belt of the radial tire does not involve the initial stage in which a fine crack generated at the end of the reinforcing element progresses along the surface of the reinforcing element. When the reinforcing elements are arranged in parallel at equal intervals according to the above, there is a disadvantage that as soon as they start to grow between adjacent reinforcing elements, they are immediately connected between the laminations of the belt and suddenly expanded, thereby progressing to belt separation. . On the other hand, in the present invention, when a bundle and a bundle or a reinforcing element that does not belong to the bundle are mixed, the dispersion interval between the reinforcing element and the bundle is much wider than that in the case of the conventional equally spaced arrangement. In this way, crack propagation between the laminations of the belt, which does not lead to crack growth between reinforcing elements adjacent to each other at the dispersion interval, and thus rapidly progresses to belt separation thereafter, is effectively suppressed.

Further, in the first aspect, by shifting the reinforcing elements in the bundle in the radial direction of the tire, it is possible to delay the growth rate of the crack in the initial stage which propagates between the reinforcing elements in the bundle. That is, the cracks in the initial stage propagate along the surface of the reinforcement element, and the propagation path follows a complicated path complicated by the displacement of the reinforcement element in the bundle in the radial direction of the tire, and as a result, the surface area of the development path that circles the bundle Becomes larger and the crack growth speed becomes much slower. This effect is exerted when the bundle thickness exceeds one time the diameter of the reinforcing element.

However, if the reinforcing elements in the bundle are excessively shifted in the radial direction of the tire, especially when a plurality of belt layers are provided, the reinforcing elements between the upper and lower belt layers may be provided under the condition that the thickness of the belt layers is not increased. The gap becomes smaller, the rubber that fills the gap, the strain generated during the rolling of the tire is concentrated, a bundle or a crack around the reinforcement element is connected, and this may progress to the belt separation as a nucleus, The bundle thickness needs to be less than twice the reinforcing element diameter.

The dispersion interval of the bundle does not need to be constant in the circumferential direction of the tread, and may vary in the circumferential direction as long as the basic performance of the belt is not impaired.

Here, only a small number of the reinforcing elements of the total number of reinforcing elements between the rubberized layers are bundled, and even if the distributed arrangement is made so as to be substantially uniform over the entire circumference of the tire, the bundle and the adjacent Since the spacing between the reinforcing elements and the reinforcing elements to be formed is wider than the spacing between the reinforcing elements when the reinforcing elements are arranged at regular intervals according to the related art, the propagation of cracks between the stacked layers of the belt, which rapidly progresses to the belt separation, is suppressed. However, the effect may not be remarkable in some cases, so that the bundle is divided into at least half or more of the reinforcing elements around the entire circumference, and the effect is remarkable.

The reason why the number of reinforcing elements in the bundle is set to several or less is that the larger the number is, the more the dispersion interval can be widened, and it is advantageous. However, it is necessary to use at most several bundles because of the disadvantage of crack propagation occurring in the bundle.

Next, in the second invention, a non-wrapping cord is applied to the above-mentioned distributed arrangement for each bundle to avoid crack propagation. Here, the non-wrap code is used for the following reason. When a steel cord or an organic fiber cord is arranged in a bundle, when the wrap filament is wound around the cord, the movement of the bundle is facilitated by the propagation of cracks in the bundle with an increase in the traveling distance. In this case, cracks originating from the wrap filaments located between the adjacent cords are generated, and these cracks are connected between the adjacent cords, and eventually become separations between belt layers, losing the advantage of arranging the cords in a bundle. Will be

That is, when conventional cords are driven at equal intervals, the presence or absence of a wrapped filament does not matter, but when the cords are arranged in a bundle, the bundle is as if it were one.
Although it functions as a book cord, when cracks grow around this bundle, the movement of the bundle increases, and the strain concentrates on the rubber that comes into contact with the wrap filament, especially where the spacing between the cords in the bundle is small. The problem is that the crack spreads as a starting point or a nucleus. Therefore, by using a non-wrap cord, the cause of the crack expansion is removed, and the above-mentioned effect of the bundle of cords is maintained.

[0021]

【Example】

Example 1 of Example 1 The tread reinforcing belt 2 of the radial tire 1 for a passenger car of size 185/70 R14 shown in cross section in FIG. Various arrangements of the reinforcing elements in the case of using the belt treat are illustrated in cross sections orthogonal to the axial direction of the reinforcing elements of the tread reinforcing belt 2 in FIGS. It is a bunch.

The tread reinforcing belt 2 is a conventional example shown in each upper part (a) of FIGS. 2 to 4 and FIG. 6 even though the arrangement of the reinforcing elements 3 in the rubberized layer is all equal. On the other hand, as shown in a different example of the present invention in each lower stage (b), as the divided bundles 4 of several reinforcing elements 3, the reinforcing elements 3 are arranged at a wider interval as compared with the conventional equidistant arrangement of the reinforcing elements. ing. Further, in the case of the present invention, the reinforcing elements 3 constituting each bundle 4 are shifted in the radial direction of the tire so that the bundle thickness L is larger than the diameter of the reinforcing elements 3. FIG. 2 shows an example in which a belt having the illustrated dispersed arrangement is applied to one layer of the tread reinforcing belt 2, and FIG. 3 shows an example in which a belt having the illustrated dispersed arrangement is applied to the two-layer belt. FIG. 6B shows an example in which the bundle thickness L is twice or more the diameter of the reinforcing element.

Each of the test tires shown in Table 1 below, which was manufactured by using various reinforcing elements according to the above, has an internal pressure of 1.9 kg.
Under a condition of f / cm ² and a load of 455 kg, a belt tester was dissected after running 60,000 km at a speed of 80 km / h on a drum tester.
Table 1 also shows the results of measuring the length of the crack generated near the width end of the sample.

[0024]

[Table 1]

In this example, two belts 2 are laminated.
The reinforcing elements of each layer cross each other at 24 ° to the tire equatorial plane, and the width of the tread side layer is slightly smaller than that of the carcass side layer.

Example 1-2 As a tread reinforcing belt 2 for a radial tire for trucks and buses of size 10.00 R20 whose cross section is shown in FIG. 15, prototypes were produced using various reinforcing elements. The test tire was run on a drum tester at a speed of 60 km / h for 100,000 km under the conditions of an internal pressure of 7.00 kgf / cm ² and a load of 2600 kg, and then dissected. The crack length generated near the width end of the belt 2 Table 2 also shows the measurement results.

[0027]

[Table 2]

In this example, four belts 2 are laminated in this example.
The reinforcement element of each layer is 18 ° left from the tread side, 18 ° left,
It is inclined to the tire equatorial plane by 18 ° right and 50 ° right. The above-mentioned cracks generated near the belt width end are generated only between the second layer from the tread side and the upper and lower layers. Therefore, the measurement results are for only the tread side layer. Based on this fact, it is of course possible to apply the rubberized layer of the present invention only to the belt on the tread side. FIG. 7B shows an example in which the bundle thickness L is twice or more the diameter of the reinforcing element. FIG. 8C shows an example in which less than half of the entire circumference is divided into bundles with respect to the conventional example shown in FIG. FIG.
(b). The manner of stacking the belts is not limited to 1 and 2 of the first embodiment, and may be, for example, a stack as shown in FIGS.

Example 2 1 The tread reinforcing belt 2 of the radial tire 1 for a passenger car of size 185/70 R14 whose cross section is shown in FIG. The various arrangements of the steel cords in the case of using the belt treat constituted by the non-wrap cord 5 described above are illustrated in FIGS. 16 to 18 in cross sections orthogonal to the reinforcing element axial direction of the tread reinforcing belt 2 in FIGS. did.

The tread reinforcing belt 2 is a conventional example shown in each upper part (a) of FIGS. 16 to 18. In the conventional example, the arrangement of the steel cords 3 in the rubberized layer is equal to each other.
Similarly, as shown in a different case of the present invention in each lower row (b), the non-wrapped cords 5 are arranged at a wider interval as compared with the conventional steel cords at regular intervals as the divided bundles 4 every several cords. I have. 17 (b) shows an example in which less than half of the entire circumference is divided into bundles, and an example in which more than half of the entire circumference is divided into bundles. Figure 18
(b).

Each of the test tires shown in Table 3 below, which was manufactured by using various steel cords according to the above,
Under a condition of 1.9 kgf / cm ² and a load of 455 kg, the test piece was run on a drum tester at a speed of 80 km / h for 60,000 km, dissected, and the length of a crack generated near a width end of the belt 2 was measured. The results are also shown in Table 3.

[0032]

[Table 3]

In this example, two belts 2 are laminated, and
The steel cords of each layer cross each other at 24 ° to the tire equatorial plane, and the width of the tread layer is slightly smaller than that of the carcass layer. The cracks generated near the width end of the belt are generated only in the tread-side layer, and the measurement results are obtained only for the tread-side layer. Based on this fact, it is of course possible to apply the rubberized layer of the present invention only to the belt on the tread side.

Example 2-2 A tread reinforcing belt 2 of a radial tire for trucks and buses of size 10.00 R20, the cross section of which is shown in FIG.
Each of the test tires shown in Table 4 below was trial-produced using various steel cords shown in FIGS. 19 to 22, and the internal pressure was 7.00 kgf / c.
m ² and a load of 2400 kg, a speed of 6
After running 100,000 km at 0 km / h, the belt was dissected and the length of the crack generated near the width end of the belt 2 was measured. 21 (b) shows an example in which less than half of the entire circumference is divided into bundles, and an example in which more than half of the entire circumference is divided into bundles. Is shown in FIG. 22 (b).

[0035]

[Table 4]

In this example, four belts 2 are laminated in this example.
Steel cord of each layer is 18 ° left from the tread side, left
18 °, right 18 ° and right 50 ° are inclined to the tire equatorial plane. The cracks generated near the width end of the belt described above are generated only in the second layer from the tread side, and therefore, the measurement results are also obtained only for the layer on the tread side. Based on this fact, it is of course possible to apply the rubberized layer of the present invention only to the belt on the tread side.

[0037]

According to the present invention, cracks in the vicinity of the end of the reinforcing element used for the reinforcing element of the belt, which is the cause of separation at the width end of the belt, which has been regarded as a weak point of reinforcing the tread of the pneumatic radial tire, are considered. Growth can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a test tire for a passenger car.

FIG. 2 is a schematic view showing an arrangement of reinforcing elements.

FIG. 3 is a schematic view showing an arrangement of reinforcing elements.

FIG. 4 is a schematic view showing an arrangement of reinforcing elements.

FIG. 5 is a schematic view showing an arrangement of reinforcing elements.

FIG. 6 is a schematic view showing an arrangement of reinforcing elements.

FIG. 7 is a schematic view showing an arrangement of reinforcing elements.

FIG. 8 is a schematic diagram showing an arrangement of reinforcing elements.

FIG. 9 is a schematic view showing an arrangement of reinforcing elements.

FIG. 10 is a schematic view showing an arrangement of reinforcing elements.

FIG. 11 is a schematic view showing an arrangement of reinforcing elements.

FIG. 12 is a schematic diagram showing an arrangement of reinforcing elements.

FIG. 13 is a schematic view showing an arrangement of reinforcing elements.

FIG. 14 is a schematic view showing an arrangement of reinforcing elements.

FIG. 15 is a cross-sectional view of a test tire for trucks and buses.

FIG. 16 is a schematic diagram showing an arrangement of reinforcing elements.

FIG. 17 is a schematic view showing an arrangement of reinforcing elements.

FIG. 18 is a schematic view showing an arrangement of reinforcing elements.

FIG. 19 is a schematic view showing an arrangement of reinforcing elements.

FIG. 20 is a schematic view showing an arrangement of reinforcing elements.

FIG. 21 is a schematic view showing an arrangement of reinforcing elements.

FIG. 22 is a schematic view showing an arrangement of reinforcing elements.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tire 2 belt for reinforcing tread 3 reinforcing element 4 bundle 5 non-wrap cord

Claims (10)

(57) [Claims] 1. A steel cord, an organic fiber cord or an organic fiber, which is obliquely parallel to the equatorial plane of the tire.
A pneumatic radial tire provided with a belt provided for tread reinforcement of a tire, comprising a rubberized layer of a reinforcing element made of a monofilament , wherein at least one layer of the belt has an individual independent structure occupying the layer. a reinforcing element
Chi, classification child the more reinforcing element half in each bunch within a few
By this, the dispersion interval between the bundle and the reinforcing element adjacent to the bundle , each reinforcing element when the reinforcing elements are arranged at equal intervals
Is an array of reinforcing elements Ru spread than the spacing between, shifting at least one of the reinforcing elements in each bundle in the tire radial direction
The bundle thickness defined by the distance between the line that contacts the outermost and the innermost line in the tire radial direction of each bundle among the lines parallel to the contour of the belt layer in which each bundle is embedded, A pneumatic radial tire wherein the diameter of the reinforcing element is more than one time and less than two times. 2. The radial tire according to claim 1, wherein the bundle comprises the same number of reinforcing elements. 3. The radial tire according to claim 1, wherein the bundle is composed of different numbers of reinforcing elements. 4. The radial tire according to claim 1, wherein at least some of the reinforcing elements adjacent to each other in the bundle are arranged in contact with each other. 5. The radial tire according to claim 4, wherein the spacing between adjacent reinforcing elements in the bundle is arranged smaller than the dispersion interval of the bundle. 6. A pneumatic radial tire having a belt layer used for reinforcing a tread of a tire as a rubberized layer of cords obliquely arranged in parallel to an equatorial plane of the tire, wherein at least one of the belt layers is vital structure with no wrap filament code among the code isolated individually occupying that layer, by partitioning the above code half for each bundle within several, a code which is adjacent the bundle and to The above code is arranged at equal intervals
A pneumatic radial tire characterized by comprising a spacing sequence Ru spread compared to between the code when. 7. A bundle comprising the same number of codes.
The radial tire according to 1. 8. The radial tire according to claim 6, wherein the bundle is made of a different number of cords . 9. At least a portion of the code adjacent in the bundle
9. The array according to claim 6, 7 or 8, wherein the electrodes are arranged in contact with each other.
The radial tire according to 1. 10. The radial tire according to claim 9, wherein an interval between adjacent cords in the bundle is arranged to be smaller than a dispersion interval of the bundle.